The present invention relates to a device which is used for spraying a pressurized liquid, in particular water, and which can achieve a very good cleaning effect despite a very low volume flow. Such a device may be designed, in particular, as a mouthpiece for sanitary outflow fittings or as an insert for a showerhead or the like.
In many areas on Earth, water is a precious commodity which has to be used sparingly. Devices which limit the volume flow of the water running through outflow fittings, showerheads, or the like can make an important contribution here. It is also the case in aircraft, camper vehicles, etc., that it may be important to be economical with the water available.
Nowadays, sanitary outflow fittings usually have mouthpieces inserted therein which mix air into the water as it exits. On one hand, this makes the outflowing jets pleasantly soft. On the other hand, it can significantly reduce the volume flow of water. Typical values for the volume flow (the flow rate) are currently approximately 12 l/min (liters per minute) for bathroom vanities. So-called economy nozzles can reduce this value to approximately 6-8 l/min. However, significantly lower volume flows are still desirable.
For this purpose, the prior art has proposed introducing the water into a swirl chamber in which the water is made to execute a swirling movement. Subsequent axial acceleration through a nozzle opening generates a finely dispersed jet, which gives a good cleaning action even in the case of a low volume flow.
Such a swirl chamber is disclosed, for example, in RU 2 196 205. The swirl chamber presented therein is conical. The water is fed to the swirl chamber, in the region of the largest cross section of the cone, through a tangential inflow channel and leaves the swirl chamber through an axial outlet channel.
A swirl chamber is also disclosed in WO 2008/073062. This document discloses a mouthpiece which is intended for a sanitary outflow fitting and can be switched between an economy mode and a normal mode. In economy mode, the water is introduced tangentially through two channels, from opposite sides, into a short, cylindrical swirl chamber, from which it exits axially through a central outlet opening. In normal mode, in contrast, the water bypasses the swirl chamber to reach the central outlet opening and also a plurality of further, decentralized outlet openings, and therefore a very much greater volume flow is achieved.
While the use of a swirl chamber can help reduce the volume flow greatly, the cleaning action which can be achieved thereby can still be improved.
A quite different approach has been pursued in WO 2007/062536. That document has proposed, among other things, allowing two water jets to strike against one another at high speed, and at a relatively large angle, to form a thin disc of water. This disc disperses at a certain distance from the point of impact to form fine droplets. A disadvantage with this device is that the water requires a very high pressure in order to ensure sufficient atomization. The document mentions a preferred pressure range of 15-25 bar, whereas the normal mains pressure is merely approximately 2-5 bar. This usually necessitates the use of a separate pump. The high pressure and the resulting extremely high exit speed of the water jets also requires special measures in order to prevent the situation where the water jets come into direct contact with the user's skin or eyes without having been atomized beforehand.
U.S. Pat. No. 5,358,179 discloses a spray head which is intended for spraying high-viscosity liquids and, in one embodiment, has swirl chambers. The liquid jets exiting from the swirl chambers then come into contact with one another.
EP 1 277 516 and WO 93/23174 each disclose a spray head with two nozzles, which have swirl channels and are directed towards one another such that the resulting jets come into contact with one another.